Fishermen's View on the Importance of the Participation of Dolphins in Artisanal Fishing in Two Estuaries in Southern Brazil

Abstract

The coastal population of common bottlenose dolphin, Tursiops truncatus, locally called "boto", presents a unique relationship with the cast net artisanal fishermen in some estuaries in southern Brazil, called human-dolphin cooperative fishery. However, these regions have been facing many environmental and socio-cultural changes in recent decades. In order to know the current view of fishermen on this interaction with the species, 40 artisanal fishermen from the estuaries of the Tramandaí and Mampituba rivers were interviewed in 2018, using a semi-structured questionnaire. In addition, on-site observations were also made during the human-dolphin cooperative fishery. The interviews and field observations revealed that cooperative fishing occurs more frequently and with the participation of a greater number of dolphins and fishermen in the estuary of the Tramandaí River than in the Mampituba River. Whereas about a dozen dolphins regularly inhabit the Tramandaí River estuary, fishermen on the Mampituba River have reported that, in recent years, only one dolphin uses the inner portion of the estuary. The lower frequency of dolphins in this last location seems to be reflecting the loss of some historical ties of this interaction, such as the naming of the dolphins by the fishermen. However, in general, the high importance given to dolphins and the perception of threats to this species and estuarine fishing resources are quite similar in the two locations. Clearly, the valorization of artisanal fishing and local ecological knowledge is fundamental for the conservation of the coastal dolphin populations in the region.